1. Field of the Invention
The present invention relates to a magnetic recording medium, such as a magnetic tape. More specifically, the present invention relates to a magnetic recording medium that has undergone anti-fungus treatment.
2. Prior Art
Generally, the magnetic layer of a magnetic recording medium is formed by coating a magnetic paint, obtained by dispersing and blending ferromagnetic powders, binders, dispersants, and lubricants in organic solvents, on a non-magnetic substrate, such as a polyester film, or by directly depositing a ferromagnetic metal through a technique such as vacuum deposition. It is also widely practiced to provide a so-called backcoat layer on the other side of the non-magnetic substrate. The backcoat layer is formed by mixing electroconductive carbon black in a binder. This is effective in preventing a loose winding or electrification of the tape, reducing the dropout or friction coefficient, improving running stability, and reducing a transfer of the lubricant from the magnetic layer.
Typically, the binder for the magnetic recording medium consists of synthetic resins, such as vinyl chloride-vinyl acetate-vinyl alcohol copolymer, cellulose derivatives, epoxy resins, polyvinyl butyral, polyurethane resins, synthetic rubber resins, acrylic resins, and polyester resins.
In the magnetic layer and the backcoat layer, described above, various additives, such as dispersants, lubricants, and anti-static agents, are utilized. These are usually a variety of organic compounds such as fatty acids and derivatives thereof, for example fatty acid esters, fatty acid metal salts or fatty acid amides, aliphatio alcohols, and other organic compounds having saturated and unsaturated hydrocarbon groups.
Some of these binders and additives contain compounds that can function as a source of nutrition for fungi. In this regard, certain fungi can grow on these layers by gradually decomposing and absorbing these compounds. When a fungus does grow in the magnetic recording media that utilize these compounds, it can cause the magnetic layer to peel off due to adhesion of tapes to each other, head contamination, deterioration in the tape smoothness and signal errors of the tape or disk. Fungus that grow on these layers can include Aspergillus, Penicillium (blue mold), and Paesilomyces.
To suppress the generation of these fungi or molds, U.S. Pat. No. 4,698,280 discloses a technique that includes adding various anti-fungus agents into the binder of the magnetic layer.
However, the anti-fungus effect of the conventional magnetic recording medium may not be sufficient and there is a demand for the development of a magnetic recording medium having a more potent anti-fungus effect.